Odd Fire TBI

**dave w** · 08-09-2016

I'm curious about your data logging and tuning plans? Identical VE Tables in both '7747's? Identical Spark Table in both 7747's? Two Laptops with two ALDL cables? One Laptop with two TunerPro RT sessions running?

dave w

**skandolis** · 08-09-2016

Very interested, lots of cool factor. what's the firing strategy,IE: will tach signals be right? is three cylinder firing possible on 7747? curious to learn how those things are gonna share fueling/mapping. I love oddball stuff, especially bringing it into the modern age........

**Willys43** · 08-09-2016

Originally Posted by skandolis

Very interested, lots of cool factor. what's the firing strategy,IE: will tach signals be right? is three cylinder firing possible on 7747? curious to learn how those things are gonna share fueling/mapping. I love oddball stuff, especially bringing it into the modern age........

Tach signal is picked up off of the distributor which still has six pulses so i think it will work. 1227747 ECU is software programmable for 3 cyl engine. I am using mapping for a stock 4.3. My 198 is a 3.2 which is almost exactly 74% of a 4.3 so I've reduced the base fuel pulse width of the 4.3 to 74%. It starts and I haven't got the foggyest idea what will happen next. Time will tell.

**lionelhutz** · 08-09-2016

Originally Posted by Willys43

It starts and I haven't got the foggyest idea what will happen next.

I love the 1 step at a time approach. No matter what system you're working with you've got to get it running before you can worry about doing anything more. It's the only way to learn and you're doing a good job on such an oddball system.

**1project2many** · 08-09-2016

Originally Posted by lionelhutz

I love the 1 step at a time approach. No matter what system you're working with you've got to get it running before you can worry about doing anything more. It's the only way to learn and you're doing a good job on such an oddball system.

Agreed. Getting it to run is a good plateau to rest on. Fuel pressure at 12-13 psi is good. I'd aim for as much common ground between the two systems as possible. Do you have the info to change the number of cylinders to three? I can dig that up...

**dave w** · 08-09-2016

Originally Posted by 1project2many

Agreed. Getting it to run is a good plateau to rest on. Fuel pressure at 12-13 psi is good. I'd aim for as much common ground between the two systems as possible. Do you have the info to change the number of cylinders to three? I can dig that up...

When I change the cylinder select value, Hex address 0016 changes. I think changing the Hex value to 03 would be the correct value?

See attached screen shot for an example of a 3 cylinder BPW (1.9 liters is half of a 3.8 liter V6 / figuring two 45 lb TBI injectors).

dave w

**1project2many** · 08-10-2016

knumcyl is a divisor and lower number of cylinders results in a higher value. Three cylinder is 96d or 60h.

**Willys43** · 08-09-2016

Im planning on staying with idntical tables, spark and ve. The laptop i have isnt much. I'll start without the ability to compare one ecu to the other. The harness has an extra injctor wire in it so I can change 1 wire and run both injectors off the same ecu if nescesary. I'm probably just going to drive the same route twice and log both just for grins and see what I get. Really accurate comparison isnt it? I lke the idea of 1 laptop, 2 cables, running to copies of Tunerpro RT. I just hate to buy another laptop. I could tune it ith 1 ECU controlling the fuel the prgram both ECUs the same and switch the injector back. Actually I don't think it should matter much which way I do it.

**Six_Shooter** · 08-09-2016

Originally Posted by dave w

I'm curious about your data logging and tuning plans? Identical VE Tables in both '7747's? Identical Spark Table in both 7747's? Two Laptops with two ALDL cables? One Laptop with two TunerPro RT sessions running?

dave w

Two sessions of Tuner Pro is possible, but not connected to two separate devices from each session. Only one session at a time can be connected to external hardware. This can be a bit annoying when you are trying to connect with a second session and forget that the first session is still "connected" (hardware not released) when trying to quickly switch back and forth. This goes for both emulation and datalogging. Got caught on that one a few times. :/

There is dual emulator support for in TunerPro RT used with Nissans that use split VE tables, but not sure if that is locked to Nissan applications or not. Whole tables should be uploaded to both Ostrichs, but Mark (that writes TunerPro) would know better how it's configured. But by the time you buy two Ostrich 2.0s and get everything set up, a Megasquirt 2 that will natively run an odd fire engine would be more cost effective and work better in the end. *shrug* '7747s are not known for high speed calculations, so staying in sync between a pair of them I still believe is going to be an issue when the engine gets some load on it.